The competition from illegal immigrants also drives down salaries for poor Americans, the commissioners said in their letter.

Their letter cited research by Julie Hotchkiss, an economist and policy adviser at the Federal Reserve Bank of Atlanta. She concluded that competition from illegal immigrants from 2000 to 2007 dropped wages for leisure and hospitality workers by 9.1 percent, and by 2.9 percent for workers in Georgia.

“Due deliberation should be given to what effect such grant will have on the employment and earnings prospects of low-skill Americans generally and black Americans specifically,” the letter concluded.

“We respectfully submit that granting such legal status is not without substantial costs to American workers.”